Rotary locking screw plug



Dec. 28, 1948. w. J. SHERMAN, SR

ROTARY LOCKING SCREW PLUG Filed Aug. 19, 1946 I INV EN TOR. 1/2/7752??? cf 57267277522, 57

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ATI'D R N EYE Patented Dec. 28, 1948 UNITED STATES PATENT OFFICE ROTARY LOCKING SCREW PLUG William J. Sherman, Sr., New Albany, Ind.

7 Application August 19, 1946", Serial No. 691,419

2 Claims. 1

My present invention relates generally to improvements in electrical connectors of the screwplug type, and more specifically to a rotary lock-- ing screw plug having means operated by an at tachable connector plug for coupling and uncouplin-g complementary terminals for making and breaking an electric circuit.

The primary object of the invention is the provision of a modified form of the well known screw plug for insertion in a socket or outlet wallbox and a detachable connector plug for socket connection with the screw plug, whereby the connector plug may be securely coupled to the screw plug for electrical connection by means of a quick-detachable fastener or catch.

The specific electrical connector of my invention is especially designed and adapted for use with the extension cords or cables of electric irons, washing machines, and other electrically operated appliances, to prevent accidental detachment of the connector plug from the screw plug, and to insure effective contact between these two members of the connector.

In carrying out my invention the screw-plug is provided with a pair of stationary terminals and a partially rotatable head, and the detach able connector plug is provided with a complementary pair of terminals that co-act with the head for making and breaking the electrical circuit through the terminals, and, in addition, the two sets of terminals are interlocked to provide a quick-detachable fastening to prevent withdrawal of the detachable plug from the screw plug.

The invention consists essentially in certain novel combinations and arrangements of these parts as will hereinafter be more fully set forth and claimed.

In the accompanying drawings I have illustrated one complete example of the physical embodiment of my invention wherein the parts are combined and arranged in accord with one mode I have devised for the practical application of the principles of my invention, butit will be understood that various changes and alterations are contemplated and may be made in these exemplifying drawings and mechanical structures, within the scope of my appended claims, without departing from the principles of my invention.

Figure 1 is a view in side elevation of a connector in which my invention is embodied.

Figure 2 is a view showing the detachable connector plug in elevation, with the screw plug in longitudinal section.

Figure 3 is a transverse sectional view through the housing and the partially rotatable head, as at line 33 of Fig. 2.

Figure 4 is a transverse sectional view at line 4- of Fig. 2 showing the complementary pairs of terminals of the two plug-sections interlocked.

Figure 5 is a detail sectional view showing the interlocking arrangement of the terminals.

Figure 6 is a perspective view of the specific type of detachable connector plug of my invention.

In the preferred form of the invention as disclosed in the drawings I employ a screw plug including'a cylindrical housing I of insulating material, which is provided at one end with an exterior threaded metal cap 2 that is adapted to be screwed into an electrical wall socket or outlet box, and the usual copper washer 3 and insulated fiber washer 4 are affixed at the front face of the plug by the con-tact pin 5 having one end embedded in the housing.

One of a pair of terminal or conductor blades 6 is connected to the pin 5, and the other, spaced blade 1 is electrically connected to the insulated r screw cap. These spring blades 6 and l are mounted in slots of the housing I and their respective free ends 8 and 9 are fashioned with return bends, loops, or hooks located in diametrically arranged recesses or sockets IU of the housing, to form stationary terminals.

The rear end of the housing I of the screw plug terminates in an integral flange l2 that forms an interior open-end cylindrical chamber or bearing seat for an oscillatible or partially rotatable block or cylindrical head I3 of insulating material that is disposed transversely of the 1ongitudinal axis of the connector, and is adapted to be turned or twisted on its axis.

The oscillatible head is retained in its chamber against longitudinal displacement, and its oscillating movement about its axis is limited, by resiliently applied detents as best seen in Fig. 3, where a pair of axially alined pins or detents M are diametrically spaced in a transverse bore of the head, and these detents are separated by an interposed spring I5.

The spring pressed detents or pins are projected outwardly so that when they are held Within the opposite ends of the bore against tension of the spring, the head may be inserted within its bearing seat or flange l2. The interior surface of the cylindrical flange is provided with a pair of diametrically arranged, arcuate, grooves 5 which are adapted to receive and retain the outer ends of the detent pins I4, and these grooves are of ample length to permit the head or block to be given a turn or twist of approximately oneeighth of a complete revolution.

As best seen in Figs. 2 and 3 the cylindrical partially rotatable head I3 is fashioned with a or, to which the extension cord or cable 29 is attached at one end, While the other end of the cord is attached to an electrically operated appliance.

lhe conductor prongs and the conuctor blades are brought into frictional contact for making an electrical contact in the electrical circuit, and in addition means are provided for interlocking the prongs and blades in electrical contactto prevent displacement of the connector plug or slide plug. For this purpose the looped or bent ends 8 and 9 of the blades 9 and l co-act with oppositely opening notches 21 of the prongs,

which notches, preferably are flared at their open ends.

After the screw plug of the connector has been inserted and secured in its socket or outlet box,

the detachable plug i9 is applied thereto by sliding the prongs i8 through the grooves ll of the partially rotatable head; then, by a clockwise turn through approximately a one-eighth revolution the detachable plug with its prongs and the head are turned to position of Fig. 1 where the grooved or notched prongs are interlocked with the hook ends of the conductor blades of the screw plug, for making the circuit and fastening the plug l9 against displacement. For breaking the circuit and uncoupling the prongs from the blades, a reverse turn is given to the plug I9.

4 and if desired, plug l9 may be detached from the screw plug.

Having thus fully described my invention, what I claim as new and desire to secure by Letters Patent is:

1. In an electrical connector, the combination with a pair of stationary conductor blades forming spaced terminals, of rotatable head adjoining said terminals a transverse bore in said head, diametrically opposed arcuate shaped grooves in said connector, spring-pressed detents in said bore co-acting with the grooves in the connector for limiting movement of the head, a detachable plug having spaced conductor prongs mounted in and projecting through the head for electrical connection with the blades, and coacting means on the prongs and blades for locking said members together.

2. In an electrical connector, the combination with a pair of conductor blades having hooked ends, of a rotatable head adjoining said ends, a transverse bore in said head, diametrically opposed arcuate shaped grooves in said connector spring-pressed detents in said bore co-acting with the grooves in the connector to limit movement of the head, a detachable plug havingspaced conductor prongs mounted in and projecting through the head for electrical connection with the blades, and said prongs having notches for mechanical engagement with said hooked ends. I

REFERENCES CITED g The following references are ofrecord in the file of this patent:

UNITED STATES PATENTS Allen Dec. 12, 1939 WILLIAM J. SHERMAN, SR. 7 

